1. Field of the Invention
Embodiments of the invention relate to a method to detect external noise using a motion sensor signal for example to increase the specificity of arrhythmia detections based on active muscle noise detection, specifically and not by way of limitation, embodiments improve the specificity of the arrhythmia detection by active detection of lead or device movement associated with electromedical implants. The electromedical implant can, for example, be an appropriately configured implantable loop recorder or ILR for long terming monitoring of electrocardiograms or ECGs or other implantable pacemaker or an implantable cardioverter/defibrillator or ICD, or any combination thereof.
2. Description of the Related Art
The primary purpose of implantable loop recorders or ILRs is the detection and/or monitoring of cardiac arrhythmia such as ventricular tachycardia or VT, atrial tachycardia or AT, ventricular fibrillation or VF, or asystole or syncope. The detection of these types of arrhythmia episodes is often impaired by cardiac unrelated disturbances such as muscle movement related noise and/or external noise. Due to these types of noise, the evaluation and/or analysis of the subcutaneous electrocardiogram or SECG with respect to detection of arrhythmia episodes is often mislead and unspecific. For example, arm movement leads to muscle noise, which is detected as a high frequent signal and potentially recognized as VT. Another example is the false detection of syncope due to under sensing of low amplitude SECG.
Currently, ILRs are sensitive in detecting arrhythmia but not very specific, i.e., are subject to a high number of false positives. These false detections introduce inefficiencies with respect to post analysis logistical efforts to schedule patient visits and significantly impair the diagnostic use of ILRs. Some studies show that overall specificity of ILRs is about 15% and even worse for high ventricular rates where specificity of ILR's drops to 0.3%.